[Q] Kernels and flashing custom ROM

I'm new to this Galaxy Note device and a bit confused about some requirements i read about flashing roms.

Several makes mention about that it works only for a specific kernel. How do I find out which kernel I have?
The phone currently is on paranoandroid 4.2.2 custom rom. Since it's a bit lagging, i want to flash it to a new better rom.
I'm unsure if I can simply download any custom rom and flash it or should I flash a specific kernel prior?

Also if you have any recommended rom with stock s-pen functionality would be great.

Thanks.